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Friebel J, Schinnerling K, Weigt K, Heldt C, Fromm A, Bojarski C, Siegmund B, Epple HJ, Kikhney J, Moter A, Schneider T, Schulzke JD, Moos V, Schumann M. Uptake of Tropheryma whipplei by Intestinal Epithelia. Int J Mol Sci 2023; 24:ijms24076197. [PMID: 37047170 PMCID: PMC10094206 DOI: 10.3390/ijms24076197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 03/18/2023] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
Background: Tropheryma whipplei (TW) can cause different pathologies, e.g., Whipple’s disease and transient gastroenteritis. The mechanism by which the bacteria pass the intestinal epithelial barrier, and the mechanism of TW-induced gastroenteritis are currently unknown. Methods: Using ex vivo disease models comprising human duodenal mucosa exposed to TW in Ussing chambers, various intestinal epithelial cell (IEC) cultures exposed to TW and a macrophage/IEC coculture model served to characterize endocytic uptake mechanisms and barrier function. Results: TW exposed ex vivo to human small intestinal mucosae is capable of autonomously entering IECs, thereby invading the mucosa. Using dominant-negative mutants, TW uptake was shown to be dynamin- and caveolin-dependent but independent of clathrin-mediated endocytosis. Complementary inhibitor experiments suggested a role for the activation of the Ras/Rac1 pathway and actin polymerization. TW-invaded IECs underwent apoptosis, thereby causing an epithelial barrier defect, and were subsequently subject to phagocytosis by macrophages. Conclusions: TW enters epithelia via an actin-, dynamin-, caveolin-, and Ras-Rac1-dependent endocytosis mechanism and consecutively causes IEC apoptosis primarily in IECs invaded by multiple TW bacteria. This results in a barrier leak. Moreover, we propose that TW-packed IECs can be subject to phagocytic uptake by macrophages, thereby opening a potential entry point of TW into intestinal macrophages.
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Affiliation(s)
- Julian Friebel
- Department of Cardiology, Angiology and Intensive Care Medicine, Deutsches Herzzentrum der Charité, 12203 Berlin, Germany
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Katina Schinnerling
- Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370146, Chile
| | - Kathleen Weigt
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Claudia Heldt
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Anja Fromm
- Institute of Clinical Physiology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Christian Bojarski
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Britta Siegmund
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Hans-Jörg Epple
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Judith Kikhney
- Institute for Microbiology, Infectious Diseases, and Immunology, Biofilmcenter, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
- MoKi Analytics GmbH, 12207 Berlin, Germany
| | - Annette Moter
- Institute for Microbiology, Infectious Diseases, and Immunology, Biofilmcenter, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
- German Konsiliarlabor for Tropheryma whipplei, 10117 Berlin, Germany
- Moter Diagnostics, 12207 Berlin, Germany
| | - Thomas Schneider
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Jörg D. Schulzke
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
- Institute of Clinical Physiology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Verena Moos
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
| | - Michael Schumann
- Department of Gastroenterology, Infectiology and Rheumatology, Campus Benjamin Franklin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 12203 Berlin, Germany
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, 10117 Berlin, Germany
- Correspondence: ; Tel.: +49-30-450-513536
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Bhandari S, Adhikari S, Karki D, Chand AB, Sapkota S, Dhungel B, Banjara MR, Joshi P, Lekhak B, Rijal KR. Antibiotic Resistance, Biofilm Formation and Detection of mexA/mexB Efflux-Pump Genes Among Clinical Isolates of Pseudomonas aeruginosa in a Tertiary Care Hospital, Nepal. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2021.810863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Efflux-pump system and biofilm formation are two important mechanisms Pseudomonas aeruginosa deploys to escape the effects of antibiotics. The current study was undertaken from September 2019 to March 2020 at a tertiary-care hospital in Kathmandu in order to ascertain the burden of P. aeruginosa in clinical specimens, examine their biofilm-forming ability and determine their antibiotic susceptibility pattern along with the possession of two efflux-pump genes-mexA and mexB. Altogether 2820 clinical specimens were collected aseptically from the patients attending the hospital and processed according to standard microbiological procedures. Identification of P. aeruginosa was done by Gram stain microscopy and an array of biochemical tests. All the P. aeruginosa isolates were subjected to in vitro antibiotic susceptibility testing and their biofilm-forming ability was also examined. Presence of mexA and mexB efflux-pump genes was analyzed by Polymerase Chain Reaction (PCR) using specific primers. Out of 603 culture positive isolates, 31 (5.14%) were found to be P. aeruginosa, of which 55% were multi-drug resistant (MDR). Out of 13 commonly used antibiotics tested by Kirby-Bauer disc diffusion method, greatest resistance was shown against piperacillin-tazobactam 15 (48.4%) and ceftazidime 15 (48.4%), and least against meropenem 6 (19.4%) and ofloxacin 5 (16.2%). Of all 17 MDR isolates subjected to biofilm detection, strong biofilm formation was exhibited by 11 (65%) and 14 (82%) isolates with microtiter plate method and tube method respectively. Out of 17 isolates tested, 12 (70.6%) isolates possessed mexA and mexB genes indicating the presence of active efflux-pump system. Higher number of the isolates recovered from sputum 7 (58.3%) and pus 5 (41.7%) possessed mexA/mexB genes while the genes were not detected at all in the isolates recovered from the urine (p<0.05). This study assessed no significant association between biofilm production and multi-drug resistance (p>0.05). Adoption of stern measures by the concerned authorities to curb the incidence of multi-drug resistant and biofilm-forming isolates is recommended to prevent their dissemination in the hospital settings.
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Molecular Mechanisms Involved in Pseudomonas aeruginosa Bacteremia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:325-345. [DOI: 10.1007/978-3-031-08491-1_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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Wagener BM, Hu R, Wu S, Pittet JF, Ding Q, Che P. The Role of Pseudomonas aeruginosa Virulence Factors in Cytoskeletal Dysregulation and Lung Barrier Dysfunction. Toxins (Basel) 2021; 13:776. [PMID: 34822560 PMCID: PMC8625199 DOI: 10.3390/toxins13110776] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/24/2021] [Accepted: 10/28/2021] [Indexed: 12/19/2022] Open
Abstract
Pseudomonas (P.) aeruginosa is an opportunistic pathogen that causes serious infections and hospital-acquired pneumonia in immunocompromised patients. P. aeruginosa accounts for up to 20% of all cases of hospital-acquired pneumonia, with an attributable mortality rate of ~30-40%. The poor clinical outcome of P. aeruginosa-induced pneumonia is ascribed to its ability to disrupt lung barrier integrity, leading to the development of lung edema and bacteremia. Airway epithelial and endothelial cells are important architecture blocks that protect the lung from invading pathogens. P. aeruginosa produces a number of virulence factors that can modulate barrier function, directly or indirectly, through exploiting cytoskeleton networks and intercellular junctional complexes in eukaryotic cells. This review summarizes the current knowledge on P. aeruginosa virulence factors, their effects on the regulation of the cytoskeletal network and associated components, and molecular mechanisms regulating barrier function in airway epithelial and endothelial cells. A better understanding of these processes will help to lay the foundation for new therapeutic approaches against P. aeruginosa-induced pneumonia.
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Affiliation(s)
- Brant M. Wagener
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Division of Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ruihan Hu
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Internal Medicine, Guiqian International General Hospital, Guiyang 550024, China
| | - Songwei Wu
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jean-Francois Pittet
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Division of Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Qiang Ding
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Pulin Che
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; (B.M.W.); (R.H.); (S.W.); (J.-F.P.); (Q.D.)
- Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Morin CD, Déziel E, Gauthier J, Levesque RC, Lau GW. An Organ System-Based Synopsis of Pseudomonas aeruginosa Virulence. Virulence 2021; 12:1469-1507. [PMID: 34180343 PMCID: PMC8237970 DOI: 10.1080/21505594.2021.1926408] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Driven in part by its metabolic versatility, high intrinsic antibiotic resistance, and a large repertoire of virulence factors, Pseudomonas aeruginosa is expertly adapted to thrive in a wide variety of environments, and in the process, making it a notorious opportunistic pathogen. Apart from the extensively studied chronic infection in the lungs of people with cystic fibrosis (CF), P. aeruginosa also causes multiple serious infections encompassing essentially all organs of the human body, among others, lung infection in patients with chronic obstructive pulmonary disease, primary ciliary dyskinesia and ventilator-associated pneumonia; bacteremia and sepsis; soft tissue infection in burns, open wounds and postsurgery patients; urinary tract infection; diabetic foot ulcers; chronic suppurative otitis media and otitis externa; and keratitis associated with extended contact lens use. Although well characterized in the context of CF, pathogenic processes mediated by various P. aeruginosa virulence factors in other organ systems remain poorly understood. In this review, we use an organ system-based approach to provide a synopsis of disease mechanisms exerted by P. aeruginosa virulence determinants that contribute to its success as a versatile pathogen.
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Affiliation(s)
- Charles D Morin
- Centre Armand-Frappier Santé Biotechnologie, Institut National De La Recherche Scientifique (INRS), Laval, Quebec, Canada
| | - Eric Déziel
- Centre Armand-Frappier Santé Biotechnologie, Institut National De La Recherche Scientifique (INRS), Laval, Quebec, Canada
| | - Jeff Gauthier
- Département De Microbiologie-infectiologie Et Immunologie, Institut De Biologie Intégrative Et Des Systèmes (IBIS), Université Laval, Québec City, Quebec, Canada
| | - Roger C Levesque
- Département De Microbiologie-infectiologie Et Immunologie, Institut De Biologie Intégrative Et Des Systèmes (IBIS), Université Laval, Québec City, Quebec, Canada
| | - Gee W Lau
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, US
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Pseudomonas Aeruginosa Induced Cell Death in Acute Lung Injury and Acute Respiratory Distress Syndrome. Int J Mol Sci 2020; 21:ijms21155356. [PMID: 32731491 PMCID: PMC7432812 DOI: 10.3390/ijms21155356] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 12/27/2022] Open
Abstract
Pseudomonas aeruginosa is an important opportunistic pathogen responsible for the cause of acute lung injury and acute respiratory distress syndrome. P. aeruginosa isthe leading species isolated from patients with nosocomial infection and is detected in almost all the patients with long term ventilation in critical care units. P. aeruginosa infection is also the leading cause of deleterious chronic lung infections in patients suffering from cystic fibrosis as well as the major reason for morbidity in people with chronic obstructive pulmonary disease. P. aeruginosa infections are linked to diseases with high mortality rates and are challenging for treatment, for which no effective remedies have been developed. Massive lung epithelial cell death is a hallmark of severe acute lung injury and acute respiratory distress syndrome caused by P. aeruginosa infection. Lung epithelial cell death poses serious challenges to air barrier and structural integrity that may lead to edema, cytokine secretion, inflammatory infiltration, and hypoxia. Here we review different types of cell death caused by P. aeruginosa serving as a starting point for the diseases it is responsible for causing. We also review the different mechanisms of cell death and potential therapeutics in countering the serious challenges presented by this deadly bacterium.
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Rehman S, Grigoryeva LS, Richardson KH, Corsini P, White RC, Shaw R, Portlock TJ, Dorgan B, Zanjani ZS, Fornili A, Cianciotto NP, Garnett JA. Structure and functional analysis of the Legionella pneumophila chitinase ChiA reveals a novel mechanism of metal-dependent mucin degradation. PLoS Pathog 2020; 16:e1008342. [PMID: 32365117 PMCID: PMC7224574 DOI: 10.1371/journal.ppat.1008342] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 05/14/2020] [Accepted: 01/22/2020] [Indexed: 12/18/2022] Open
Abstract
Chitinases are important enzymes that contribute to the generation of carbon and nitrogen from chitin, a long chain polymer of N-acetylglucosamine that is abundant in insects, fungi, invertebrates and fish. Although mammals do not produce chitin, chitinases have been identified in bacteria that are key virulence factors in severe respiratory, gastrointestinal and urinary diseases. However, it is unclear how these enzymes are able to carry out this dual function. Legionella pneumophila is the causative agent of Legionnaires' disease, an often-fatal pneumonia and its chitinase ChiA is essential for the survival of L. pneumophila in the lung. Here we report the first atomic resolution insight into the pathogenic mechanism of a bacterial chitinase. We derive an experimental model of intact ChiA and show how its N-terminal region targets ChiA to the bacterial surface after its secretion. We provide the first evidence that L. pneumophila can bind mucins on its surface, but this is not dependent on ChiA. This demonstrates that additional peripheral mucin binding proteins are also expressed in L. pneumophila. We also show that the ChiA C-terminal chitinase domain has novel Zn2+-dependent peptidase activity against mammalian mucin-like proteins, namely MUC5AC and the C1-esterase inhibitor, and that ChiA promotes bacterial penetration of mucin gels. Our findings suggest that ChiA can facilitate passage of L. pneumophila through the alveolar mucosa, can modulate the host complement system and that ChiA may be a promising target for vaccine development.
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Affiliation(s)
- Saima Rehman
- Centre for Host-Microbiome Interactions, Dental Institute, King’s College London, London, United Kingdom
| | - Lubov S. Grigoryeva
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Katherine H. Richardson
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Paula Corsini
- Centre for Host-Microbiome Interactions, Dental Institute, King’s College London, London, United Kingdom
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Richard C. White
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Rosie Shaw
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Theo J. Portlock
- Centre for Host-Microbiome Interactions, Dental Institute, King’s College London, London, United Kingdom
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Benjamin Dorgan
- Centre for Host-Microbiome Interactions, Dental Institute, King’s College London, London, United Kingdom
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Zeinab S. Zanjani
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Arianna Fornili
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Nicholas P. Cianciotto
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - James A. Garnett
- Centre for Host-Microbiome Interactions, Dental Institute, King’s College London, London, United Kingdom
- Chemistry and Biochemistry Department, School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
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Bohn E, Sonnabend M, Klein K, Autenrieth IB. Bacterial adhesion and host cell factors leading to effector protein injection by type III secretion system. Int J Med Microbiol 2019; 309:344-350. [DOI: 10.1016/j.ijmm.2019.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 05/02/2019] [Accepted: 05/31/2019] [Indexed: 01/14/2023] Open
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Bogiel T, Deptuła A, Kwiecińska-Piróg J, Prażyńska M, Mikucka A, Gospodarek-Komkowska E. The Prevalence of Exoenzyme S Gene in Multidrug-Sensitive and Multidrug-Resistant Pseudomonas aeruginosa Clinical Strains. Pol J Microbiol 2019; 66:427-431. [PMID: 29313517 DOI: 10.5604/01.3001.0010.6500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa rods are one of the most commonly isolated microorganisms from clinical specimens, usually responsible for nosocomial infections. Antibiotic-resistant P. aeruginosa strains may present reduced expression of virulence factors. This fact may be caused by appropriate genome management to adapt to changing conditions of the hospital environment. Virulence factors genes may be replaced by those crucial to survive, like antimicrobial resistance genes. The aim of this study was to evaluate, using PCR, the occurrence of exoenzyme S-coding gene (exoS) in two distinct groups of P. aeruginosa strains: 83 multidrug-sensitive (MDS) and 65 multidrug-resistant (MDR) isolates. ExoS gene was noted in 72 (48.7%) of the examined strains: 44 (53.0%) MDS and 28 (43.1%) MDR. The observed differences were not statistically significant (p = 0.1505). P. aeruginosa strains virulence is rather determined by the expression regulation of the possessed genes than the difference in genes frequency amongst strains with different antimicrobial susceptibility patterns.
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Affiliation(s)
- Tomasz Bogiel
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Aleksander Deptuła
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Joanna Kwiecińska-Piróg
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Małgorzata Prażyńska
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Agnieszka Mikucka
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
| | - Eugenia Gospodarek-Komkowska
- Department of Microbiology, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, Poland
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Laventie BJ, Sangermani M, Estermann F, Manfredi P, Planes R, Hug I, Jaeger T, Meunier E, Broz P, Jenal U. A Surface-Induced Asymmetric Program Promotes Tissue Colonization by Pseudomonas aeruginosa. Cell Host Microbe 2018; 25:140-152.e6. [PMID: 30581112 DOI: 10.1016/j.chom.2018.11.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/28/2018] [Accepted: 10/22/2018] [Indexed: 12/24/2022]
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa effectively colonizes host epithelia using pili as primary adhesins. Here we uncover a surface-specific asymmetric virulence program that enhances P. aeruginosa host colonization. We show that when P. aeruginosa encounters surfaces, the concentration of the second messenger c-di-GMP increases within a few seconds. This leads to surface adherence and virulence induction by stimulating pili assembly through activation of the c-di-GMP receptor FimW. Surface-attached bacteria divide asymmetrically to generate a piliated, surface-committed progeny (striker) and a flagellated, motile offspring that leaves the surface to colonize distant sites (spreader). Cell differentiation is driven by a phosphodiesterase that asymmetrically positions to the flagellated pole, thereby maintaining c-di-GMP levels low in the motile offspring. Infection experiments demonstrate that cellular asymmetry strongly boosts infection spread and tissue damage. Thus, P. aeruginosa promotes surface colonization and infection transmission through a cooperative virulence program that we termed Touch-Seed-and-Go.
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Affiliation(s)
| | - Matteo Sangermani
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Fabienne Estermann
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Pablo Manfredi
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | | | - Isabelle Hug
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Tina Jaeger
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | | | - Petr Broz
- Department of Biochemistry, University of Lausanne, Lausanne, Switzerland
| | - Urs Jenal
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland.
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The Pseudomonas aeruginosa PilSR Two-Component System Regulates Both Twitching and Swimming Motilities. mBio 2018; 9:mBio.01310-18. [PMID: 30042200 PMCID: PMC6058289 DOI: 10.1128/mbio.01310-18] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Motility is an important virulence trait for many bacterial pathogens, allowing them to position themselves in appropriate locations at appropriate times. The motility structures type IV pili and flagella are also involved in sensing surface contact, which modulates pathogenicity. In Pseudomonas aeruginosa, the PilS-PilR two-component system (TCS) regulates expression of the type IV pilus (T4P) major subunit PilA, while biosynthesis of the single polar flagellum is regulated by a hierarchical system that includes the FleSR TCS. Previous studies of Geobacter sulfurreducens and Dichelobacter nodosus implicated PilR in regulation of non-T4P-related genes, including some involved in flagellar biosynthesis. Here we used transcriptome sequencing (RNA-seq) analysis to identify genes in addition to pilA with changes in expression in the absence of pilR. Among the genes identified were 10 genes whose transcription increased in the pilA mutant but decreased in the pilR mutant, despite both mutants lacking T4P and pilus-related phenotypes. The products of these inversely dysregulated genes, many of which were hypothetical, may be important for virulence and surface-associated behaviors, as mutants had altered swarming motility, biofilm formation, type VI secretion system expression, and pathogenicity in a nematode model. Further, the PilSR TCS positively regulated transcription of fleSR, and thus many genes in the FleSR regulon. As a result, pilSR deletion mutants had defects in swimming motility that were independent of the loss of PilA. Together, these data suggest that in addition to controlling T4P expression, PilSR could have a broader role in the regulation of P. aeruginosa motility and surface sensing behaviors. Surface appendages such as type IV pili and flagella are important for establishing surface attachment and infection in a host in response to appropriate cues. The PilSR regulatory system that controls type IV pilus expression in Pseudomonas aeruginosa has an established role in expression of the major pilin PilA. Here we provide evidence supporting a new role for PilSR in regulating flagellum-dependent swimming motility in addition to pilus-dependent twitching motility. Further, even though both pilA and pilR mutants lack PilA and pili, we identified sets of genes downregulated in the pilR mutant and upregulated in a pilA mutant as well as genes downregulated only in a pilR mutant, independent of pilus expression. This finding suggests that change in the inner membrane levels of PilA is only one of the cues to which PilR responds to modulate gene expression. Identification of PilR as a regulator of multiple motility pathways may make it an interesting therapeutic target for antivirulence compounds.
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Crane MJ, Lee KM, FitzGerald ES, Jamieson AM. Surviving Deadly Lung Infections: Innate Host Tolerance Mechanisms in the Pulmonary System. Front Immunol 2018; 9:1421. [PMID: 29988424 PMCID: PMC6024012 DOI: 10.3389/fimmu.2018.01421] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/07/2018] [Indexed: 12/16/2022] Open
Abstract
Much research on infectious diseases focuses on clearing the pathogen through the use of antimicrobial drugs, the immune response, or a combination of both. Rapid clearance of pathogens allows for a quick return to a healthy state and increased survival. Pathogen-targeted approaches to combating infection have inherent limitations, including their pathogen-specific nature, the potential for antimicrobial resistance, and poor vaccine efficacy, among others. Another way to survive an infection is to tolerate the alterations to homeostasis that occur during a disease state through a process called host tolerance or resilience, which is independent from pathogen burden. Alterations in homeostasis during infection are numerous and include tissue damage, increased inflammation, metabolic changes, temperature changes, and changes in respiration. Given its importance and sensitivity, the lung is a good system for understanding host tolerance to infectious disease. Pneumonia is the leading cause of death for children under five worldwide. One reason for this is because when the pulmonary system is altered dramatically it greatly impacts the overall health and survival of a patient. Targeting host pathways involved in maintenance of pulmonary host tolerance during infection could provide an alternative therapeutic avenue that may be broadly applicable across a variety of pathologies. In this review, we will summarize recent findings on tolerance to host lung infection. We will focus on the involvement of innate immune responses in tolerance and how an initial viral lung infection may alter tolerance mechanisms in leukocytic, epithelial, and endothelial compartments to a subsequent bacterial infection. By understanding tolerance mechanisms in the lung we can better address treatment options for deadly pulmonary infections.
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Affiliation(s)
| | | | | | - Amanda M. Jamieson
- Division of Biology and Medicine, Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, United States
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Golovkine G, Reboud E, Huber P. Pseudomonas aeruginosa Takes a Multi-Target Approach to Achieve Junction Breach. Front Cell Infect Microbiol 2018; 7:532. [PMID: 29379773 PMCID: PMC5770805 DOI: 10.3389/fcimb.2017.00532] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/20/2017] [Indexed: 01/17/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen which uses a number of strategies to cross epithelial and endothelial barriers at cell–cell junctions. In this review, we describe how the coordinated actions of P. aeruginosa's virulence factors trigger various molecular mechanisms to disarm the junctional gate responsible for tissue integrity.
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Affiliation(s)
- Guillaume Golovkine
- Centre National de la Recherche Scientifique ERL5261, CEA BIG-BCI, Institut National de la Santé et de la Recherche Médicale UMR1036, Université Grenoble Alpes, Grenoble, France
| | - Emeline Reboud
- Centre National de la Recherche Scientifique ERL5261, CEA BIG-BCI, Institut National de la Santé et de la Recherche Médicale UMR1036, Université Grenoble Alpes, Grenoble, France
| | - Philippe Huber
- Centre National de la Recherche Scientifique ERL5261, CEA BIG-BCI, Institut National de la Santé et de la Recherche Médicale UMR1036, Université Grenoble Alpes, Grenoble, France
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Hayashi N, Yokotani A, Yamamoto M, Kososhi M, Morita M, Fukunishi C, Nishizawa N, Gotoh N. Extracellular Signals of a Human Epithelial Colorectal Adenocarcinoma (Caco-2) Cell Line Facilitate the Penetration of Pseudomonas aeruginosa PAO1 Strain through the Mucin Layer. Front Cell Infect Microbiol 2017; 7:415. [PMID: 28983473 PMCID: PMC5613098 DOI: 10.3389/fcimb.2017.00415] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 09/06/2017] [Indexed: 01/25/2023] Open
Abstract
Pseudomonas aeruginosa can penetrate the layer of mucus formed by host intestinal epithelial cells, often resulting in sepsis in immunocompromised patients. We have previously demonstrated that P. aeruginosa can penetrate the mucin layer by flagellar motility and the degradation of the mucin layer. However, it remains unclear how P. aeruginosa initially recognizes epithelial cells. Using the human epithelial colorectal adenocarcinoma (Caco-2) cell line, we investigated extracellular signaling that could facilitate the penetration of P. aeruginosa through the mucin layer. The supernatant from Caco-2 cell cultures increased penetration of P. aeruginosa through an artificial mucin layer. The Caco-2 cell supernatant increased bacterial flagella-dependent swarming motility, but it did not influence P. aeruginosa growth or protease activity. Filtering of the Caco-2 cell supernatant indicated that proteins weighing <10 kDa increased mucin penetration, swarming motility, and, based on a tethered cell assay, induced acceleration of the flagellar filament rotational rate. Furthermore, a capillary assay showed that <10 kDa proteins in the Caco-2 cell supernatant attracted P. aeruginosa cells. Finally, we identified that growth-regulated oncogene-α (GRO-α) secreted by Caco-2 cells was a factor facilitating flagellar filament rotation and swarming motility, although it did not attract the bacteria. We conclude that penetration of the mucin layer by P. aeruginosa is facilitated by small proteins (<10 kDa) secreted by Caco-2 cells, both by inducing acceleration of flagellar motility and increasing chemotaxis.
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Affiliation(s)
- Naoki Hayashi
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Atsushi Yokotani
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Masami Yamamoto
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Mariko Kososhi
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Mayu Morita
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Chiaki Fukunishi
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Nagisa Nishizawa
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
| | - Naomasa Gotoh
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical UniversityKyoto, Japan
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Wei L, Wu R, Wang C, Wu Z. Effects of ε-Polylysine on Pseudomonas Aeruginosa and Aspergillus Fumigatus Biofilm In Vitro. Med Sci Monit 2017; 23:4225-4229. [PMID: 28863128 PMCID: PMC5592802 DOI: 10.12659/msm.903145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Background The antimicrobial mechanisms of ɛ-polylysine (EPL) against Pseudomonas aeruginosa and Aspergillus fumigatus biofilm were investigated. Material/Methods We assessed the changes in electric conductivity of broth and total sugar concentration, as well as changes in phosphorous metabolism and protein expression, of the 2 organisms before and after treatment with EPL. Results The experimental results showed that EPL has antimicrobial activity against Pseudomonas aeruginosa and Aspergillus fumigatus, but the activity was much stronger for the former. After treatment with EPL, the electric conductivity and total sugar concentration of microbial broth increased, suggesting that EPL damages the cell membrane structure, which increases permeability of the cell membrane and release of cell components. Conclusions The consumption of phosphorous decreased in the EPL-treated organisms, which seriously affected the synthesis of important cell components such as nucleic acid and phospholipid, as well as energy metabolism.
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Affiliation(s)
- Lianhua Wei
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, China (mainland).,Clinical Laboratory Centre of Gansu Provincial Hospital, Lanzhou, Gansu, China (mainland)
| | - Run Wu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, China (mainland)
| | - Chuan Wang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, China (mainland)
| | - Zixiang Wu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, China (mainland)
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Pseudomonas aeruginosa Pore-Forming Exolysin and Type IV Pili Cooperate To Induce Host Cell Lysis. mBio 2017; 8:mBio.02250-16. [PMID: 28119472 PMCID: PMC5263249 DOI: 10.1128/mbio.02250-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clinical strains of Pseudomonas aeruginosa lacking the type III secretion system genes employ a toxin, exolysin (ExlA), for host cell membrane disruption. Here, we demonstrated that ExlA export requires a predicted outer membrane protein, ExlB, showing that ExlA and ExlB define a new active two-partner secretion (TPS) system of P. aeruginosa In addition to the TPS signals, ExlA harbors several distinct domains, which include one hemagglutinin domain, five arginine-glycine-aspartic acid (RGD) motifs, and a C-terminal region lacking any identifiable sequence motifs. However, this C-terminal region is important for the toxic activity, since its deletion abolishes host cell lysis. Using lipid vesicles and eukaryotic cells, including red blood cells, we demonstrated that ExlA has a pore-forming activity which precedes cell membrane disruption of nucleated cells. Finally, we developed a high-throughput cell-based live-dead assay and used it to screen a transposon mutant library of an ExlA-producing P. aeruginosa clinical strain for bacterial factors required for ExlA-mediated toxicity. The screen resulted in the identification of proteins involved in the formation of type IV pili as being required for ExlA to exert its cytotoxic activity by promoting close contact between bacteria and the host cell. These findings represent the first example of cooperation between a pore-forming toxin of the TPS family and surface appendages in host cell intoxication. IMPORTANCE The course and outcome of acute, toxigenic infections by Pseudomonas aeruginosa clinical isolates rely on the deployment of one of two virulence strategies: delivery of effectors by the well-known type III secretion system or the cytolytic activity of the recently identified two-partner secreted toxin, exolysin. Here, we characterize several features of the mammalian cell intoxication process mediated by exolysin. We found that exolysin requires the outer membrane protein ExlB for export into extracellular medium. Using in vitro recombinant protein and ex vivo assays, we demonstrated a pore-forming activity of exolysin. A cellular cytotoxicity screen of a transposon mutant library, made in an exolysin-producing clinical strain, identified type IV pili as bacterial appendages required for exolysin toxic function. This work deciphers molecular mechanisms underlying the activity of novel virulence factors used by P. aeruginosa clinical strains lacking the type III secretion system, including a requirement for the toxin-producing bacteria to be attached to the targeted cell to induce cytolysis, and defines new targets for developing antivirulence strategies.
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Cai S, Li Y, Wang K, Cen Y, Lu H, Dong B, Chen Y, Kong J. Pathogenic Effects of Biofilm on Pseudomonas Aeruginosa Pulmonary Infection and Its Relationship to Cytokines. Med Sci Monit 2016; 22:4869-4874. [PMID: 27941713 PMCID: PMC5156558 DOI: 10.12659/msm.898783] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background An animal (Sprague-Dawley rat) model of Pseudomonas aeruginosa biofilm associated with chronic pulmonary infection in vivo was established and the effects of the biofilm on P. aeruginosa and its relationship to cytokines were investigated. Material/Methods Biofilm of P. aeruginosa in alginate beads and planktonic PA0725 were purified by anion-exchange chromatograph. Sprague-Dawley (SD) rats were immunized with the biofilm and then inhaled the same strain of P. aeruginosa. Anti-biofilm antibody titer was detected using the enzyme linked immunosorbent assay (ELISA) method. The cell count and differential count in the bronchoalveolar lavage fluid (BALF) were measured. The levels of cytokines (IL-17, IL-1β, MIP-2, and G-CSF) and tumor necrosis factor (TNF)-α in sera were also measured using an ELISA kit. Results The sera anti-biofilm IgG antibody titer of immunized SD rats was increased significantly on the 5th and 8th days after inhalation. The IL-17 concentration was significantly higher on the 8th day after inhalation. The results indicated that when biofilm-pre-immunized rats were challenged with inhalation of PA0725 of P. aeruginosa, the biofilm acted as an antigen substance and mediated the antibody reaction of the antigen, which might cause serious airway inflammatory response and lung tissue injury. This effect may be related to IL-17. Conclusions P. aeruginosa biofilm protected the bacterium from antibiotics and might induce host immune damage in lung tissue and facilitate bacterium evading the host barrier.
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Affiliation(s)
- Shuangqi Cai
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Yanan Li
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Ke Wang
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Yanling Cen
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Huasong Lu
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Biying Dong
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Yiqiang Chen
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
| | - Jinliang Kong
- Department of Respiratory Disease, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China (mainland)
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Shikata M, Hayashi N, Fujimoto A, Nakamura T, Matsui N, Ishiyama A, Maekawa Y, Gotoh N. The pilT gene contributes to type III ExoS effector injection into epithelial cells in Pseudomonas aeruginosa. J Infect Chemother 2016; 22:216-20. [PMID: 26809217 DOI: 10.1016/j.jiac.2015.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 12/16/2015] [Accepted: 12/19/2015] [Indexed: 01/12/2023]
Abstract
A type IV pilus filament, mainly composed of PilA, is retracted by the driving power generated by PilT and PilU ATPases. pilA is required for injection of type III ExoS effectors into epithelial cells thereby facilitating Pseudomonas aeruginosa penetration through the epithelial barrier by impairing the defense function of tight junctions. Here, we examined whether the pilT and pilU of the P. aeruginosa PAO1 strain are required for ExoS injection into epithelial cells. We measured the quantity of ExoS injected into epithelial cells, and found that within such cells its quantity decreased by 80% (ΔpilA strain), 75% (ΔpilT strain), and 30% (ΔpilU strain) compared with the wild-type strain. pilT deficiency decreased the disruption of human epithelial colorectal adenocarcinoma (Caco-2) cell monolayers to the same extent as that of pilA and exoS deficiency, whereas pilU deficiency decreased disruption of the monolayers less than deficiency of the other genes. pilT and pilU deficiency decreased bacterial penetration of the Caco-2 cell monolayers to the same level as pilA and exoS deficiency. Our data showed that the pilU gene expression level was reduced in the PAO1 strain after adhesion to Caco-2 cell surfaces, but the expression levels of the pilA and pilT genes did not change. We conclude that P. aeruginosa injects ExoS into cells through the function of type IV pilus retraction, and that pilT makes a greater contribution to this process than pilU.
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Affiliation(s)
- Mototsugu Shikata
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Naoki Hayashi
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Akiyo Fujimoto
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Takano Nakamura
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Naoyuki Matsui
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Ayana Ishiyama
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Yui Maekawa
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan
| | - Naomasa Gotoh
- Department of Microbiology and Infection Control Science, Kyoto Pharmaceutical University, Yamashina, Kyoto 607-8414, Japan.
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Pseudomonas aeruginosa Transmigrates at Epithelial Cell-Cell Junctions, Exploiting Sites of Cell Division and Senescent Cell Extrusion. PLoS Pathog 2016; 12:e1005377. [PMID: 26727615 PMCID: PMC4699652 DOI: 10.1371/journal.ppat.1005377] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/09/2015] [Indexed: 12/19/2022] Open
Abstract
To achieve systemic infection, bacterial pathogens must overcome the critical and challenging step of transmigration across epithelial barriers. This is particularly true for opportunistic pathogens such as Pseudomonas aeruginosa, an agent which causes nosocomial infections. Despite extensive study, details on the mechanisms used by this bacterium to transmigrate across epithelial tissues, as well as the entry sites it uses, remain speculative. Here, using real-time microscopy and a model epithelial barrier, we show that P. aeruginosa employs a paracellular transmigration route, taking advantage of altered cell-cell junctions at sites of cell division or when senescent cells are expelled from the cell layer. Once a bacterium transmigrates, it is followed by a cohort of bacteria using the same entry point. The basal compartment is then invaded radially from the initial penetration site. Effective transmigration and propagation require type 4 pili, the type 3 secretion system (T3SS) and a flagellum, although flagellum-deficient bacteria can occasionally invade the basal compartment from wounded areas. In the basal compartment, the bacteria inject the T3SS toxins into host cells, disrupting the cytoskeleton and focal contacts to allow their progression under the cells. Thus, P. aeruginosa exploits intrinsic host cell processes to breach the epithelium and invade the subcellular compartment. In normal situations, the mucosae constitute efficient barriers against the invasion of opportunistic pathogens. The bacteria inducing nosocomial infections take advantage of pre-existing pathological situations to cross the epithelium and spread in deeper tissues. The conditions on the host side permitting transmigration and the combination of virulence factors used by the bacteria to transmigrate are mostly speculative. Here, we studied the transmigration process of Pseudomonas aeruginosa, a bacterium causing hospital-acquired acute and chronic infections. We found that bacteria exploits weakened cell-cell junctions of the epithelium, such as those generated at sites of cell division or when dying cells are extruded from the cell layer, to breach the cell layer, using specific virulence factors and motility appendages.
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